Did you know that there is a natural occurrence that happens around this time of the year at sunset? It is a phenomenon that you would probably never expect. Basically, the sun is setting faster during the time of an equinox. The quickest sunsets (and sunrises) happen at or around the equinoxes. And the slowest ones happen at or near the solstices. Therefore, it doesn’t matter where you live; this occurs both in the Northern and Southern Hemisphere.
Just to make thigs clear, when we mention sunset here, we’re talking about the exact amount of time it takes for the sun’s body to disappear below the western horizon.
Why is the sun setting so fast during the equinoxes?
At every equinox, the sun rises pretty much to the east and sets to the west. This means – on the day of an equinox – the setting sun reaches the horizon at its steepest point.
In the meantime, at a solstice, the sun sets farthest north or farthest south of due west. The angle of the setting sun gets shallower as the sun sets farther from due west along the horizon. This means a longer sunset period at the solstices.
The length of the sunset differs by latitude. Farther north or south on the globe of Earth, the length of sunset becomes longer. However, near the equator, the period of time is shorter. But let’s look at one latitude – 40 degrees north, the latitude of Denver or Philadelphia in the United States, and Beijing in China. At that latitude, on equinox day, the sun sets in around 2 3/4 minutes.
Moreover, the solstice sun sets at 40 degrees latitude in about 3 1/4 minutes.
When is the equinox happening?
The September equinox will occur at 13:31 UTC on September 22, 2020. Even though the equinox occurs all over the world at the same time, your clock will depend on your time zone. For time zones in the U.S. mainland, the equinox will start at 9:31 a.m. EDT on September 22, 8:31 a.m. CDT, 7:31 a.m. MDT or 6:31 a.m. PDT. You can convert to your time zone.
To sum up, the quickest sunsets of the year are arriving now, at the time of the September equinox.